Insert workflow start time

[j-woz]

We may also want to insert a start time into the log as reported by Swift using clock().

[hyoo]

i agree. timestamp from swift level would be more accurate.
BTW, we need to format it to meet the ISO standard, for example, 2017-07-05T14:51:05Z

[j-woz]

I can provide a new Swift function to produce the date in this format.
The current format used in the JSON is: 2017-07-03 17:48:54.310325

[hyoo]

yeah, that is wrong. need to change to.